Magnetic switch device



June 24, 1958 A. c. DUCATI 2,340,661

MAGNETIC SWITCH DEVICE Filed June 16, 1955 INVENTOR. ADRIANQ C. DUCATI 3 WILL,\OMI o-\\cna.

ATTORN United States Patent MAGNETIC SWITCH DEVICE Adriano C. Ducati, Milan, Italy, assignor to G. M. Giannini & Co., Inc., Pasadena, Calif.

Application June 16, 1955, Serial No. 515,987

12 Claims. (Cl. 200-87) This invention relates to magnetic switches, and particularly to an improved magnetic switch of the type having magnetizabie contact members in a sealed nonmagnetic envelope, the switch being actuated from outside the envelope by magnetizing the contacts or their supporting members.

In switches of the foregoing type, it has been customary to utilize contact members which overlap each other in one way or another, the arrangement being such that one or both members move laterally when magnetized to make the desired contact. In one common construction, for example, fiat blade type electrodes are placed in a cylindrical glass envelope positioned in a magnetizing field coil. The electrodes overlap and have sufficient resilience to move toward each other when magnetized so that their fiat faces come into contact. In such a construction, it is inevitable that there will be a substantial amount of free space between the electrodes and the envelope walls. Accordingly, a relatively strong magnetic field is required in order to traverse this free space and magnetize the contacts.

It is among the objects of the present invention to provide a more elficient electrode construction which will minimize the space between the electrodes and the field source so as to reduce the required actuating field to a minimum. The invention further contemplates an electrode construction and arrangement which lends itself readily to the provision of a single-pole, doublethrow switch as well as the more common single-pole, single-throw type.

In accordance with a preferred embodiment of the invention, the foregoing and other related objects and advantages are attained in a switch wherein the contacts are engaged and disengaged by longitudinal rather than lateral electrode movement. This makes it feasible to have electrodes that conform closely in cross sectional shape to the cross section of the envelope, thereby minimizing the spacing between the electrodes and the envelope walls. Although the principal electrode movement is longitudinal as previously stated, for some applications improved contact action can be had by beveling the contacting faces of the electrodes so that they will come together with a sliding or wiping action. In accordance with a further feature of the invention, an electrode which is movable in a sealed envelope can be positioned between two fixed contact members to serve as the switching pole in a single-pole double-throw switch. Again, the construction is such that an actuating coil wound on the enclosing envelope will be very close to the magnetic material so as to minimize the required actuating field.

A more complete understanding of the invention, and

Patented June 24, 1958 Figure 2 is a perspective view of the spring mounting arrangement for the movable electrode member in the switch of Figure l; and

Figure 3 is a partial sectional view of a switch having a beveled electrode construction.

Figure 1 of the drawing shows a magnetic switch embodying the invention and comprising a pair of elongated magnetizable electrodes 10, 12 which are of circular cross section and are formed of soft iron or other readily magnetizable material. The electrodes 10, 12 serve both as magnetic field conductors or armatures and as contact members through which electric current will flow.

One electrode, 10, is supported in relatively fixed position in one end of a cylindrical glass envelope 14 by a Kovar metal lead 16. The lead 16 is fixed by soldering, welding or the like to one end of the electrode 10 and extends through a seal in the end wall of the envelope. This provides electrical access to the electrode 10 from outside the envelope and also supports the electrode in the desired position.

The other electrode, 12, is mounted in the other end of the envelope 14 in end-to-end relation to the fixed electrode 10, and in axial alignment therewith. However, this electrode 12 is supported resiliently for longitudinal or endwise movement in the envelope, rather than being fixed in position. The supporting means for the movable electrode 12 (see Figure 2) comprises four arcuate leaves 13 of spring metal which extend endwise from the end of the electrode 12 to a Kovar metal ring 20. The spring members 18 are welded or otherwise secured in good electrical and mechanical engagement with the electrode 12 and the ring 20. The ring 20 surrounds and is sealed to a glass bead 22 which is in turn sealed to a supporting Kovar lead wire 24 passing through a seal in the adjacent end wall of the envelope 14.

An extension 24a of the lead wire 24 makes electrical contact with the adjacent end of the movable electrode 12, thereby cooperating with the electrode 12 to provide a first set of contacts (normally closed) in the switching device. In order that an electric circuit can be completed from outside the envelope through these contacts 12, 24a, a third Kovar metal lead 26 is brought through a seal in the envelope end wall and connected to the support ring 20.

Thus, when the switch is not magnetized, a circuit will be completed through the lead wire 24 (and extension 2411), the movable electrode 12, the supporting springs 18, the Kovar ring 20 and the lead wire 26.

The movable electrode 12 and its fixed counterpart 10 together constitute a second (normally open) set of contacts which can be made to close by passing electric current through a magnetizing winding, illustrated diagrammatically at 29, which surrounds the envelope 14. The magnetic field set up by current through this winding will magnetize the two electrodes 10, 12 as armatures, causing them to be attracted so that the movable elecrode 12 will move endwise and make contact with the fixed electrode 19. At the same time, of course, the contact between the lead Wire extension 24a and the movable electrode 12 will be opened.

Thus, when the switchis magnetized, the circuit through the contacts 12, 24a will be opened and a new circuit formed which includes the lead wire 26, the ring 20, the springs 18, the movable electrode 12, the fixed electrode 10 and the lead wire 16. Accordingly, it is seen that the movable electrode 12 serves as the switching pole of a single-pole, double-throw switch.

In order to prevent vibration or accidental shock from displacing the movable electrode 12 sufiiciently to make contact with the fixed electrode 10 or break contact with 7 3 the lead wire extension 24a, a resilient sleeve 30 preferably is provided. This sleeve, which also minimizes bouncing of the electrode 12 when the switch is magnetized, extends over the adjacent end portions of the electrodes 10, 12. The sleeve 30 preferably is formed of silicone rubber, although other resilient insulating material can be used. In the present illustrative example, the sleeve is formed of thin walled tubing, occupying recessed portions 10a, 12a of the electrodes to preclude any possibility of its shifting in position.

The distance between the ends of the contact electrodes 10 and 12, when the switch is not energized, depends upon the voltage and current requirements of the switch contacts and upon the desired operating speed. One important advantage ofthis arrangement is that with small electrode spacing, high switching rates can be attained.

With such close spacing, the movable electrode 12 need move only a small distance to open the contact with the lead wire extension 24a and make contact with the fixed electrode 10. The sleeve 30 will readily compress or bulge outwardly the small amount necessary to accommodate the endwise movement of the electrode 12. When the magnetizing field is removed, the electrode 12 will be helped to return to its rest position by this stressing of the sleeve 30 as well as by the restoring force of the springs 18.

In order to insure making good contact, the contact faces at the ends of the electrodes 10, 12 may be coated with highly conductive contact material, such as silver, tungsten, platinum or the like; Similarly, the lead wire extension 24a preferably will be tipped with suitable contact material welded with Kovar wire. To reduce further the possibility of corrosion of the electrodes as well as arcing at the contacts, the envelope 14 may be evacuated or may be filled with inert gas such as helium or the like.

It will be understood that the switch construction shown in Figure 1 can be modified readily to a singlepole single-throw switch, merely by eliminating the lead extension 24a. In such case the lead 26 also can be eliminated by providing a strip of contact material over the head 22 from the ring to the lead 24. Alterna-' tively, the glass head 22 can be replaced by a bead Of conductive material. Moreover, the ring 20 can be sealed directly into the end of the glass envelope 14.

Figure 3 shows a modification of the electrode structure of Figure 1 In the Figure 3 construction, the contact faces 10b, 12b of the electrodes 10, 12 are beveled at a slight angle, for example 30 degrees, rather than being perpendicular to the electrode axes. Inother respects, it can be assumed that the construction of the electrodes themselves and of their supporting structure corresponds functionally with the structure shown in Figures 1 and 2, to the extent that the electrodes 10' and 12 are relatively movable longitudinally. it will be appreciated that the spring mounting of the electrode 12', as shown in Figures 1 and 2, also will allow slight movement of the electrode 12 laterally with respect to the longitudinal axis of the assembly. Accordingly, when a switch with beveled electrode faces 16b, 1% as in Figure 3 is magnetized, the movable electrode 12 will move longitudinally until it strikes the fixed electrode 10, and then will slide or ride up slightly on the beveled face 10b with a wiping action. This will help to maintain clean, broad area contact surfaces on the faces 10b, 12b, thereby providing uniform and relatively low contact resistance. The same effect will be further promoted by the wearing in action that will occur as the switch is used.

Obviously, if only a single throw switch construction is' desired, both electrodes 10 and 12, with the configuration of either Figure l or Figure 3, can be resiliently supported for longitudinal movement.

From the foregoing it will be seen that the switch-relay 4 described above will be efiicient in operation and rapid in action and that it is subject to many modifications to permit adapting it readily to the various conditions of use.

What is claimed is:

l. A magnetic switch device comprising a sealed envelope, two members of magnetizable material inside said envelope, said members being in spaced end-to-end relationship to each other and having longitudinal axes substantially in alignment with each other, the adjacent portions of said members providing electrical contact faces in closely spaced relationship, resilient mounting means supporting one of said members spaced from the inside wall of the envelope and arranged to permit said one member to move toward and away from the other member in a longitudinal direction generally parallel to said axes, said resilient mounting means being connected to said movable member on opposite sides of its axis, and a winding outside said envelope for magnetizing said members.

2. A magnetic switch device comprising a sealed envelope, first and second electrodes of magnetizable material inside said envelope, said electrodes being in spaced relationship to each other and having longitudinal axes substantially in alignment with each other, the adjacent end portions of said electrodes forming spaced electrical contact faces, resilient mounting means supporting said first electrode in spaced relationship with the inside surface of the envelope and arranged to permit it to move toward and away from said second electrode in a direction generally parallel to said axes, an additional elec-' trical contact element mounted within said envelope normally in contact with said first electrode, said additional contact element being so located that upon movement of said first electrode toward said second electrode, said contact elementis disengaged from said first electrode and electromagnetic control means outside said envelope for magnetizing said electrodes.

3. A magnetic switch device comprising a sealed envelope, two electrodes of magnetizable material mounted in said envelope in spaced end-to-end relationship and in substantial alignment with the axis of said envelope, a plurality of resilient means secured to one of said electrodes on opposite sides of its axis for resiliently mounting said one electrode and resiliently supported free of engagement with the inner surface of the envelope and arranged for endwise movement in said envelope in a direction paralleling said envelope axis, and electromagnetic control means outside said envelope for magnetizing said electrodes.

4. A magnetic switch device as defined in claim 3, and including a sleeve of resilient flexible material surrounding the adjacent end portions of said electrodes.

5. A magnetic switch device comprising a generally cylindrical sealed envelope, two generally cylindrical electrodes'of magnetizable material inside said envelope in spacedend-to-end relationship and having their longitudinal axes substantially in alignment with each other and with the axis of said envelope, supporting means symmetrical with respect to the axis of said envelope for resiliently mounting one of said electrodes for endwise movement in a direction generally parallel to said axes and supporting said one electrode spaced away from any engagement with the inner surface of the envelope, the

cylindrical surfaces of said electrodes being closely adjacent to and spaced from the inner surface of said envelope, and a winding closely surrounding said entions forming electrical contacts overlapping each other in closely spaced relationship, means resiliently mounting and supporting one of said electrodes in spaced relationship away from the inner surface of the envelope for endwise movement within said envelope free of any engagement with the inner surface of the envelope, said resiliently mounting means comprising spring means at one end of said movable electrode and a resilient sleeve surrounding the beveled end portions and spanned therebetween, and electromagnetic control means outside sai envelope for magnetizing said electrodes, thereby to move said one electrode endwise into contact with the other electrode, said beveled ends permitting said electrical contacts to engage with a sliding action.

7. A magnetic switch device comprising a relatively long, generally cylindrical sealed envelope, a pair of rigid generally cylindrical electrodes of magnetizable material, one in each end of said envelope, said electrodes being in spaced end-to-end relationship and in substantially longitudinal axial alignment with each other, tl adjacent ends of said electrodes having beveled end portions forming electrical contacts overlapping each other in closely spaced relationship, means resiliently mounting and supporting one of said electrodes in spaced relationship away from the inner surface of the envelope for endwise movement within said envelope free of any engagement with the inner surface of the envelope, said resilient mounting and supporting means comprising a fixed support member in said envelope located between said one electrode and the adjacent envelope end wall, and a plurality of arcuate metal spring members extending from spaced points on the end of said one electrode to said support member, thereby to support said one electrode in spaced relationship away from the inner surface of the envelope, while enabling endwise movement of said one electrode free of any engagrnent with the inner surface of the envelope, and electromagntic control means outside said envelope for magnetizing said electrodes, thereby to move said one electrode endwise into contact with the other electrode, said beveled end: permitting said electrical contacts to engage with a sliding action.

8. A double-throw magnetically operable switch device comprising a sealed envelope, a pair of fixed electrical contact elements in said envelope in substantially fixe v spaced relationship to each other, one of said fixed contact elements being a rod-like element, a movable electrical contact element mounted resiliently between said pair of fixed elements and movable from a first position engaging only one of said fixed elements to a second position engaging only the other of said fixed elements, resilient mounting and supporting means spaced concentrically around said rod-like contact element and movably supporting said movable contact element free of any engagement with the envelope, said movable element and one of said fixed elements being of magnetizable material, and a magnetizing winding around said envelope.

9. A magnetic switch device comprising a sealed envelope, first and second electrodes of magnetizable material within said envelope in spaced end-to-end relationship and having longitudinal axes in substantial alignment with each other, means resiliently supporting one of said electrodes for endwise movement substantially along its longitudinal axis within said envelope into and out of engagment with the other of said electrodes free of any engagement with the inner surface of the envelope, an additional contact element mounted in said envelope and the end of said first electrode nearest the end of said envelope, and electromagnetic control means for magnetizing said electrodes, thereby to attract said electrodes toward each other to bring the adjacent ends of said electrodes into contact and simultaneously to disengage said contact element and said first electrode.

10. A magnetic switch device comprising a cylindrical sealed envelope, two elongated electrodes of magnetiz able material resiliently mounted in said envelope with their longitudinal axes in alignment with each other and with the axis of said envelope, the longitudinal surfaces of said electrodes being closely adjacent to the inner surface of said envelope, the adjacent ends of said electrodes being in normally spaced relationship, a pair of conductive support elements passing out through the opposite ends of said sealed envelope, one of said support elements comprising a metal lead extending an appreciable distance into said envelope, a bead of insulating material surrounding said lead within said envelope and spaced from the free end of said lead, a ring of conductive material surrounding said lead within said envelope and metal spring members extending from said ring to one of said electrodes and holding said one electrode resiliently in engagement with said free end of said metal lead, the other of said support elements being fixed to and supporting the other of said electrodes, and a further conductive member extending into said envelope and engaging said ring.

11. Apparatus as claimed in claim 10 wherein the adjacent end portions of said electrodes are cut off at an angle to form substantially parallel bevelled contact faces overlapping each other in normally spaced relationship.

12. A double-throw magnetically-operable switch device including a sealed cylindrical envelope, a first member of magnetizable material within said envelope in substantially fixed position, the inner end of said first member including a first electrical contact having a first external lead connected thereto, a second fixed electrical contact longitudinally spaced from said first contact and having a second external lead connected therewith, a movable cylindrical member of magnetizable material positioned between said first and second contacts, said movable member having third and fourth contacts at its opposite ends adapted selectively to engage said first and second contacts, respectively, resilient mounting and supporting means movably supporting said movable member spaced away from the inside surface of the envelope, said resilient means normally holding said second and fourth contacts together, a third external lead connected to said resilient means, and electromagnetic means outside said envelope arranged to magnetize said first member and said movable member thereby to move said third and first contacts together.

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